Persistence of Some Chlorinated Hydrocarbon Insecticides in Turf Soils1

Abstract

To determine the residual effectiveness of some chlorinated hydrocarbon insecticides for the control of Japanese beetle grubs (Popillia japonica Newm.), turf plots were treated at various concentrations in 1946 with chlordane and BHC, in 1949 with heptachlor and in 1954 with aldrin. The insecticides were applied as top dressings to the established turf and the experimental plots were left undisturbed throughout the years. In 1957 and 1958 soil samples were collected from the upper 3" soil layer. An average of 1.5% of the applied chlordane was recovered 12 years after treatment as estimated by a specific chemical analysis and an average of 12% as estimated by bioassay. Eleven years after treatment, BHC was recovered to an extent of 41% of the applied dosage as estimated by chemical analysis and to an extent of 8% as measured by bioassay. No heptachlor was recovered from soils which had been treated with heptachlor 9 years earlier, when analyzed by a specific calorimetric method. However, using a bioassay procedure, 4 to 5% of the applied toxicant was found. This toxicant proved to be heptachlorepoxide. Most of the aldrin had disappeared during a period of 4 years. However, part of the aldrin had been converted into dieldrin, which was recovered to an extent of 8 to 10% of the applied dosage. Aldrin, which had been rototilled into the soil immediately after application, persisted considerably longer, though the rate of dieldrin formation was more or less the same as compared with soils which had not been rototilled after treatment.